function [map,num,typ,scheme] = brewermap_view(N,scheme,isco)
% Create an interactive figure for viewing ColorBrewer colormaps. With demo!
%
% (c) 2014-2025 Stephen Cobeldick
%
% View Cynthia Brewer's ColorBrewer 2.0 colorschemes/palettes in a figure:
%
% * Two colorbars give the colorscheme in color and grayscale.
% * A button toggles between 3D-cube and 2D-lineplot of the RGB values.
% * A button toggles an endless demo cycle through the colorschemes.
% * A button reverses the colormap.
% * Thirty-five buttons select any ColorBrewer colorscheme.
% * Text with the colorscheme's type (Diverging/Qualitative/Sequential).
% * Text with the colorscheme's number of nodes (i.e. defining colors).
%
%%% Syntax %%%
%
%   brewermap_view
%   brewermap_view(N)
%   brewermap_view(N,scheme)
%   brewermap_view(N,scheme,isco)
%   brewermap_view([],...)
%   brewermap_view(axes/figure handle array,...) % see "Adjust Colormaps"
%   [map,num,typ] = brewermap_view(...)
%
% Calling the function with an output argument blocks MATLAB execution until
% the figure is deleted: the final colormap and parameters are then returned.
%
%% Adjust Colormaps or Colororders of Figures or Axes %%
%
% For R2014b or later: provide axes or figure handles as the first input
% and their COLORMAP will be updated in real-time by BREWERMAP_VIEW.
% For R2019b or later: set the 3rd input to TRUE to update COLORORDER.
%
%   >> S = load('spine');
%   >> image(S.X)
%   >> brewermap_view(gca) % colormap
%
%   >> plot(rand(5,7))
%   >> brewermap_view(gca,[],true) % colororder
%
%% Input Arguments (**=default) %%
%
%   N = NumericScalar, an integer to define the colormap length.
%     = []**, colormap length of two hundred and fifty-six (256).
%     = NaN, same length as the defining RGB nodes (useful for Line ColorOrder).
%     = Array of axes or figure handles. R2014b or later only.
%   scheme = CharRowVector or StringScalar, a ColorBrewer colorscheme name.
%          = []** randomly selects a colorscheme.
%   isco = LogicalScalar, true/false** updates the colororder/colormap of
%          the provided axes or figure handles.  R2019b or later only.
%
%% Output Arguments (block code execution until figure is closed) %%
%
%   map = NumericMatrix, the colormap defined when the figure is closed.
%   num = NumericVector, the number of nodes defining the ColorBrewer colorscheme.
%   typ = CharRowVector, the colorscheme type: 'Diverging'/'Qualitative'/'Sequential'.
%
%% Dependencies %%
%
% * MATLAB R2009a or later.
% * brewermap.m <www.mathworks.com/matlabcentral/fileexchange/45208>
%
% See also BREWERMAP BREWERMAP_NODES CUBEHELIX PRESET_COLORMAP MAXDISTCOLOR
% RGBPLOT COLORMAP COLORMAPEDITOR COLORBAR UICONTROL ADDLISTENER
persistent ax2D ln2D ax3D pt3D txtH is2D cbAx cbIm pTxt pSld bEig bGrp bRev scm isr
%
new = isempty(ax2D)||~ishghandle(ax2D);
dfn = 256;
upd = false;
upb = false;
hgv = [];
nmr = dfn;
%
%% Input Wrangling %%
%
if nargin>2 && isco
	% >R2019a only!
	fnh = @colororder;
else % default
	fnh = @colormap;
end
%
err = 'First input <N> must be a real positive scalar numeric or [] or NaN.';
if nargin==0 || isnumeric(N)&&isequal(N,[])
	N = dfn;
elseif isnumeric(N)
	assert(isscalar(N),'SC:brewermap_view:N:NotScalarNumeric',err)
	assert(isreal(N)&&isfinite(N)&&fix(N)==N&&N>0||isnan(N),...
		'SC:brewermap_view:N:NotRealPositiveIntegerNorNaN',err)
	N = double(N);
elseif all(ishghandle(N(:))) % R2014b or later
	assert(all(isgraphics(N(:),'axes')|isgraphics(N(:),'figure')),...
		'SC:brewermap_view:N:NotAxesNorFigureHandles',...
		'First input <N> may be an array of figure or axes handles.')
	hgv = N(:);
	nmr = arrayfun(@(h)size(fnh(h),1),hgv);
	N = nmr(1);
else
	error('SC:brewermap_view:N:UnsupportedInput',err)
end
%
[mcs,nmn,pyt] = brewermap('list');
%
% Check BREWERMAP output:
tmp = find([any(diff(double(char(pyt)),1),2);1]);
assert(isequal(tmp,[9;17;35]),'SC:brewermap_view:BREWERMAP:OutputOrder',...
	'The BREWERMAP function returned an unexpected colorscheme sequence.')
%
if nargin<2 || isnumeric(scheme)&&isequal(scheme,[])
	% Default pseudo-random colorscheme:
	isr = rand(1)>0.5;
	scm = mcs{1+mod(round(now*1e7),numel(mcs))}; %#ok<TNOW1>
else
	% Parse input colorscheme:
	scheme = bmv1s2c(scheme);
	assert(ischar(scheme) && ndims(scheme)==2 && size(scheme,1)==1,...
		'SC:brewermap_view:scheme:NotCharacterVector',...
		'Second input <scheme> must be a 1xN char vector.') %#ok<ISMAT>
	% Check if a reversed colormap was requested:
	isr = strncmp(scheme,'-',1) || strncmp(scheme,'*',1);
	isd = strncmp(scheme,'+',1) || isr;
	scm = scheme(1+isd:end);
end
%
if isnan(N)
	N = nmn(strcmpi(scm,mcs));
end
%
%% Ensure Figure Exists %%
%
% LHS and RHS slider bounds/limits, and slider step sizes:
lbd = 1;
rbd = dfn;
stp = [1,10]; % [minor,major]
%
% Define the 3D cube axis order:
xyz = 'RGB'; % specify the order here.
[~,xyz] = ismember(xyz,'RGB');
%
if new % Create a new figure.
	%
	% Figure parameters:
	M = 9; % buttons per column
	gap = 0.01; % gaps
	bth = 0.04; % demo button height
	btw = 0.10; % demo button width
	bgh = 0.40; % button group height
	cbw = 0.23; % colorbar width (both together)
	cbh = 1-3*gap-bth; % colorbar height
	axh = 1-bgh-2*gap; % axes height
	axw = 1-cbw-2*gap; % axes width
	bgw = axw-btw-gap; % button group width
	%
	figH = figure('HandleVisibility','callback',...
		'IntegerHandle','off', 'NumberTitle','off', 'Units','normalized',...
		'Name','ColorBrewer Interactive ColorScheme Selector',...
		'MenuBar','figure', 'Toolbar','none', 'Tag',mfilename);
	%
	% Add 2D lineplot:
	ax2D = axes('Parent',figH, 'Position',[gap,bgh+gap,axw,axh], 'Box','on',...
		'ColorOrder',[1,0,0; 0,1,0; 0,0,1; 0.6,0.6,0.6], 'HitTest','off',...
		'Visible','off', 'XLim',[0,1], 'YLim',[0,1], 'XTick',[], 'YTick',[]);
	ln2D = line([0,0,0,0;1,1,1,1],[0,0,0,0;1,1,1,1], 'Parent',ax2D,...
		'Visible','off', 'Linestyle','-', 'Marker','.');
	%
	% Add 3D scatterplot:
	ax3D = axes('Parent',figH, 'OuterPosition',[0,bgh,axw+2*gap,1-bgh],...
		'Visible','on', 'XLim',[0,1], 'YLim',[0,1], 'ZLim',[0,1], 'HitTest','on');
	pt3D = patch('Parent',ax3D, 'XData',[0;1], 'YData',[0;1], 'ZData',[0;1],...
		'Visible','on', 'LineStyle','none', 'FaceColor','none', 'MarkerEdgeColor','none',...
		'Marker','o', 'MarkerFaceColor','flat', 'MarkerSize',10, 'FaceVertexCData',[1,1,0;1,0,1]);
	view(ax3D,3);
	grid(ax3D,'on')
	lbl = {'Red','Green','Blue'};
	xlabel(ax3D,lbl{xyz(1)})
	ylabel(ax3D,lbl{xyz(2)})
	zlabel(ax3D,lbl{xyz(3)})
	%
	% Add warning text:
	txtH = text('Parent',ax2D, 'Units','normalized', 'Position',[1,1],...
		'HorizontalAlignment','right', 'VerticalAlignment','top');
	%
	% Add demo button:
	demo = uicontrol(figH, 'Style','togglebutton', 'Units','normalized',...
		'Position',[1-cbw/2,1-bth-gap,cbw/2-gap,bth], 'String','Demo',...
		'Max',1, 'Min',0, 'Callback',@bmvDemo); %#ok<NASGU>
	% Add 2D/3D button:
	is2D = uicontrol(figH, 'Style','togglebutton', 'Units','normalized',...
		'Position',[1-cbw/1,1-bth-gap,cbw/2-gap,bth], 'String','2D / 3D',...
		'Max',1, 'Min',0, 'Callback',@bmv2D3D);
	% Add reverse button:
	bRev = uicontrol(figH, 'Style','togglebutton', 'Units','normalized',...
		'Position',[bgw+2*gap,bgh-bth,btw,bth], 'String','Reverse',...
		'Max',1, 'Min',0, 'Callback',@bmvRevM);
	%
	% Add colorbars:
	C(1,1,:) = [1,1,1];
	cbAx(2) = axes('Parent',figH, 'Visible','off', 'Units','normalized',...
		'Position',[1-cbw/2,gap,cbw/2-gap,cbh], 'YLim',[0.5,1.5],...
		'YDir','normal', 'HitTest','off');
	cbAx(1) = axes('Parent',figH, 'Visible','off', 'Units','normalized',...
		'Position',[1-cbw/1,gap,cbw/2-gap,cbh], 'YLim',[0.5,1.5],...
		'YDir','normal', 'HitTest','off');
	cbIm(2) = image('Parent',cbAx(2), 'CData',C);
	cbIm(1) = image('Parent',cbAx(1), 'CData',C);
	%
	% Add parameter sliders, listeners, and corresponding text:
	sv = mean([lbd,rbd],2);
	pTxt = uicontrol(figH,'Style','text', 'Units','normalized',...
		'Position',[bgw+2*gap,bgh-2*bth-gap,btw,bth], 'String','X');
	pSld = uicontrol(figH,'Style','slider', 'Units','normalized',...
		'Position',[bgw+2*gap,gap,btw,bgh-2*bth-gap], 'Min',lbd(1), 'Max',rbd(1),...
		'SliderStep',stp(1,:)/(rbd(1)-lbd(1)), 'Value',sv(1));
	addlistener(pSld, 'Value', 'PostSet',@bmvSldr);
	%
	% Add colorscheme button group:
	bGrp = uibuttongroup('Parent',figH, 'BorderType','none', ...
		'Units','normalized', 'Position',[gap,gap,bgw,bgh-gap]);
	% Determine button locations:
	Z = 1:numel(mcs);
	Z = Z+(Z>17);
	C = (ceil(Z/M)-1)/4;
	R = (M-1-mod(Z-1,M))/M;
	% Add colorscheme buttons to group:
	for jj = numel(mcs):-1:1
		bEig(jj) = uicontrol('Parent',bGrp, 'Style','Toggle', 'String',mcs{jj},...
			'Unit','normalized', 'Position',[C(jj),R(jj),1/4,1/M]);
	end
	set(bGrp,'SelectionChangeFcn',@bmvChgS);
	%
end
%
%% Nested Functions %%
%
	function str = bmvName()
		% Generate the colorscheme name.
		pfx = '+-';
		ids = strcmpi(scm,mcs);
		if any(ids)
			str = [pfx(1+isr),mcs{ids}];
		else % will throw an error in BREWERMAP:
			str = scm;
		end
	end
%
	function bmvUpDt()
		% Update all graphics objects in the figure.
		%
		% Get ColorBrewer colormap and grayscale equivalent:
		[map,num,typ] = brewermap(N,bmvName());
		mag = map*[0.298936;0.587043;0.114021];
		%
		% Update colorbar values:
		set(cbAx, 'YLim',[0,abs(N)+(N==0)]+0.5);
		set(cbIm(1), 'CData',reshape(map,[],1,3))
		set(cbIm(2), 'CData', repmat(mag,[1,1,3]))
		%
		% Update 2D line / 3D patch values:
		if get(is2D, 'Value')
			set(ln2D, 'XData',linspace(0,1,abs(N)));
			set(ln2D,{'YData'},num2cell([map,mag],1).');
		else % 3D
			set(pt3D,...
				'XData',map(:,xyz(1)),...
				'YData',map(:,xyz(2)),...
				'ZData',map(:,xyz(3)),...
				'FaceVertexCData',map)
		end
		%
		% Update reverse button:
		set(bRev, 'Value',isr)
		%
		% Update warning text:
		str = {[bmvName(),' '];[typ,' '];sprintf('%d Nodes ',num)};
		set(txtH,'String',str);
		%
		% Update parameter value text:
		set(pTxt(1), 'String',sprintf('N = %.0f',N));
		%
		% Update external axes/figure colormaps/colororders:
		nmr(1) = N;
		for k = 1:numel(hgv)
			fnh(hgv(k),brewermap(nmr(k),bmvName()));
		end
		%
		drawnow()
	end
%
	function bmv2D3D(h,~)
		% Switch between 2D-line and 3D-cube representation.
		%
		if get(h,'Value') % 2D
			set(ax3D, 'HitTest','off', 'Visible','off')
			set(ax2D, 'HitTest','on',  'Visible','on')
			set(pt3D, 'Visible','off')
			set(ln2D, 'Visible','on')
		else % 3D
			set(ax2D, 'HitTest','off', 'Visible','off')
			set(ax3D, 'HitTest','on',  'Visible','on')
			set(ln2D, 'Visible','off')
			set(pt3D, 'Visible','on')
		end
		%
		bmvUpDt();
	end
%
	function bmvChgS(~,e)
		% Change the colorscheme.
		%
		scm = get(e.NewValue,'String');
		%
		bmvUpDt()
	end
%
	function bmvRevM(h,~)
		% Reverse the colormap.
		%
		isr = logical(get(h,'Value'));
		%
		bmvUpDt()
	end
%
	function bmvSldr(~,~)
		% Update the slider position.
		%
		if ~upd
			return
		end
		%
		N = round(get(pSld,'Value'));
		%
		bmvUpDt()
	end
%
	function bmvDemo(h,~)
		% Display all ColorBrewer colorschemes sequentially.
		%
		cnt = 0;
		while ishghandle(h)&&get(h,'Value')
			cnt = mod(cnt+1,pow2(53));
			%
			if mod(cnt,23)<1
				ids = 1+mod(find(strcmpi(scm,mcs)),numel(mcs));
				scm = mcs{ids};
				try %#ok<TRYNC>
					set(bGrp, 'SelectedObject',bEig(ids));
				end
			end
			%
			if mod(cnt,69)<1
				isr = ~isr;
			end
			%
			upb = (upb || N<=1) && N<dfn;
			N = N - 1 + 2*upb;
			%
			% Update slider position:
			upd = false;
			try %#ok<TRYNC>
				set(pSld, 'Value',N)
				bmvUpDt()
			end
			upd = true;
			%
			% Faster/slower:
			pause(0.1);
		end
		%
	end
%
%% Initialize the Figure %%
%
set(bGrp,'SelectedObject',bEig(strcmpi(scm,mcs)));
set(pSld,'Value',max(lbd,min(rbd,N)));
upd = true;
bmvUpDt()
%
if nargout
	waitfor(ax2D);
	scheme = bmvName();
else
	clear map
end
%
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%brewermap_view
function arr = bmv1s2c(arr)
% If scalar string then extract the character vector, otherwise data is unchanged.
if isa(arr,'string') && isscalar(arr)
	arr = arr{1};
end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%bmv1s2c
%
% Copyright (c) 2014-2025 Stephen Cobeldick
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS,
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
% See the License for the specific language governing permissions and limitations under the License.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%license